The rotation lag is a product of Froyo. It was there in the leaked version of DK28 Froyo and they didn't address it on the official release. The only real way to fix it is by rooting you phone and using an application called Terminal Emulator.
Rotation Lag Fix:
Download Terminal Emulator from the Market
Type the following
su (press enter and allow root access)
/system/bin/sensorcalibutil_yamaha (press enter)
Then it will ask for you to calibrate. I usually lay mine flat on its back with keyboard open and then press enter. Back out of program and power off the screen then wake the phone up. Lag rotation fixed.